1. Field of the Invention
This invention relates to a toner supply device and an image forming apparatus that are used in, for example, electro-photographic copiers.
2. Description of the Related Art
An image forming apparatus forms an electrostatic latent image on a photosensitive drum that is an image carrier and develops this electrostatic latent image with a developing device. A toner bottle that is a toner supply device is attached to the developing device and toners are supplied to the developing device.
A cap portion of the toner bottle is inserted into a coupling that forms a driving unit and connected to the coupling. An opening is provided on a peripheral wall of the cap portion and a toner supply opening is provided on a peripheral wall of the coupling. When the cap portion of the toner bottle is inserted into the coupling, its opening is opposed to the toner supply opening of the coupling.
When supplying a toner, the toner bottle is rotated with the rotation of the coupling and when the opening of the toner bottle and the toner supply opening is located at the lower side, a toner in the toner bottle falls by its own weight through the opening and is supplied in the developing device.
As the cap portion of the toner bottle is inserted in the coupling and fitted in the airtight state, when the toner bottle is pulled out, the pressure in the coupling changes rapidly,
However, as a hole provided so far to the coupling was only at the toner supply opening. A strong sucking power acts on the toner supply opening. Therefore, there was such a problem that toner adhered to the peripheral edge portion of the toner supply opening is sucked into the toner bottle and the inside of the coupling is contaminated.
Further, when some defect was generated and the rotation of the toner bottle was stopped during the image forming operation, operator may pull out the toner bottle erroneously at a position other than the specific position.
However, when the toner bottle was pulled out at a position other than the specific position, the coupling was so far kept in the stopped state at that position. Therefore, there was such a trouble that a time was needed to position a toner bottle against the coupling and the toner bottle could not be inserted smoothly into the coupling when reinserting the toner bottle.
Further, there are couplings that can be rotated irrespective of the presence of a toner bottle. In this case, however, there was such a problem that if the coupling was erroneously rotated without inserting a toner bottle into the coupling, a toner flows back from the toner supply opening of the coupling and is scattered by centrifugal force.